1. Field of the Invention
The present invention relates generally to the creation of heat transfer printing paper used in the process of printing cloth with various multi-colored designs and specifically to a method and apparatus for creating extra wide heat transfer printing paper.
2. Discussion of Prior Art
In the cloth printing process, it is known to utilize heat transfer printing paper to transfer cloth printing ink from a specific pattern on the paper to the cloth to be printed. In order to print cloth with the pattern on the paper, the cloth and the paper are placed together for a specific period of time under a specific pressure at a specific temperature during which time ink from the printing paper is transferred to and colors the cloth with which it is contact.
Because the heat transfer ink pattern can be precisely printed on the heat transfer printing paper, the pattern will also be accurately duplicated on the cloth printed therefrom. Conventionally, printing paper up to 64 inches in width is printed with a print width of approximately 63 inches with one or more colors in a series of successive printing stations, each of which are in registration with the other stations. This registration is important in the printing of the ink on the heat transfer printing paper so that each of the desired colors in a pattern is in precise registration with other colors in order to form a desired image.
The accuracy required for the printing of high-quality heat transfer printing paper (for high quality printing of cloth) necessitates the use of the rotogravure printing process. In this process, an individual printing drum is engraved so as to provide microscopic pits in the area where ink is to be printed on the paper. During the printing of the pattern onto the paper, the surface of the engraved roller passes through an ink bath and the pits will pick up and retain a desired quantity of ink, whereas the rest of the engraved roller will not retain any ink. The engraved roller then comes into contact with the printing paper and the capillary action of the paper transfers the ink from the pit to the paper.
Because the engraving of such rollers can be done extremely accurately, heat transfer printing paper made by the rotogravure printing process has an extremely high degree of accuracy. Such accuracy is necessary especially when the paper may be printed with 3, 6, 8 or even 10 different colors of ink.
While the 63 inch cloth width is adequate for use in clothing and other types of apparel, a wider cloth is highly desirable for use in draperies, bedspreads, etc. The need for wider cloth has created a demand for wider heat transfer print paper such that designs can be reproduced on larger widths of cloth, i.e., greater than the conventional 63 inch width.
It would seem that to satisfy the need for wider fabric, one would merely use a rotogravure roller having the larger width. However, the handling of the wider width rotogravure roller is difficult and expensive (the 126" rotogravure roller would cost more than twice the conventional smaller 63 inch print width roller). Further, it would be difficult to store the engraving rollers having the larger width. There is also a lack of machinery capable of printing onto heat transfer paper utilizing the rotogravure process at the larger width.
Attempts have been made to use a rotary screen printing process for printing heat transfer ink onto wider heat transfer print paper (up to 126 inches in width) but such process does not provide acceptable pattern accuracies, especially for highly complex, multi-colored patterns possible with the rotogravure printing process.
One attempt to satisfy the need for wider printed cloth is a machine manufactured by the Lemaire company in France in which conventional width print paper is used to print a wider width of cloth. Two rolls of conventional width printed heat transfer paper are carried along two parallel paths and are placed in contact with the cloth to be printed. The parallel paths are adjacent such that the pattern image from one parallel path is, hopefully, in precise registration with the pattern image on the other parallel path with the result that the pattern is transferred to and printed on the wider than normal cloth.
As can be imagined, such a printing process is extremely slow and is very sensitive to going off registration which results in a high degree of wastage of cloth being printed. Additionally, because of the need to attempt to maintain accurate registration, the operating speed is on the order of 7 to 8 yards of cloth per minute and the cost of such a machine is quite high ($450,000 or more). Consequently, while the Lemaire machine permits the usage of rotogravure printed conventional width paper, it suffers from the problem that the company using the paper must maintain the two parallel paths of paper in precise registration during the printed process.
Clearly, if wider paper with heat transfer ink patterns printed thereon were available, the cloth printing company would not be concerned with registration and higher speeds of printing would be available, thus providing a significant benefit to the cloth producer.